<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>addEventListener</title>
</head>
<body>
    
</body>

<script>

    let n=3600
    setInterval(()=>{
        n=n-10;
        console.log("time：",n,(n-n%60)/60)
    },1000*30)


// var passiveSupported = false;

//  try {
//   var options = Object.defineProperty({}, "passive", {
//     get: function() {
//       passiveSupported = true;
//     }
//   });
// //------------------测试options.passive 是否调用-----------------------------
//   window.addEventListener("test", null, options);
 
//  } catch(err) {}
// window.addEventListener("mouseup", null, passiveSupported
//                                ? { passive: true } : false);


</script>

</html>